The devices work by overcoming the delay in electrical conduction that occurs in a specialized network known as the left and right bundle branches. These bundle branches separate the left and right ventricles, allowing electrical signals to simultaneously stimulate both ventricles. This coordination allows for enough force to provide optimal pumping of blood to the lungs and throughout the body.

When this coordination is thrown off, electric leads can be used to electrically stimulate heart muscle to synchronize the contractions of the ventricles.